Electrical multitester



April 1951 T. L. BART'HOLOMEW 2,547,248-

ELECTRICAL MULTITESTER 3 Sheets-Sheet 1 Filed Oct. 10, 1946 e... fin.

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April 1951 1 1.. BARTHOLOMEW 2,547,248

ELECTRICAL MULTITESTER Filed Oct. 10, 1946 3 Sheets-Sheet 2 ZZZ-.2

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Atturnu v April 1951 T. L. BARTHOLOMEW 2,547,248

ELECTRICALMULTITESTER Filed Oct. 10, 1946 3 Shee'ts-Sheet 3 771oM/is L542 THOL OMEI/V.

Patented Apr. 3, 1951 UNITED STATES PATENT OFFICE ELECTRICALMHUVLTITESTER Thomas L. Bartholomew, Baltimore, 9 Application October10, 1946, Serial No. 702,546;-

1 This invention refers to testing equipment and more particularly to anelectrical measuring device suitable for taking readings of directcurrent and alternate current voltage, amperage and ohmage of anextraneous network or the elements thereof in a single portable testinginstrument.

It is an object of the present invention to provide a new and improvedtesting instrument that will avoid one or more of the disadvantagesandlimitations of the prior art.

Another object of this invention is to provide Claims. '(01. 171-95) Itected by a window I4 of glass or plastic, transa new and improvedtesting instrument that not J only will beportable but "compact, easilyread convenient to use and attractive inappe-aranee A further object or"the invention is to provide a new and improved testing'instrument thatwill embody various adjustments and conveniences that will facilitateits-use for the purposes intended for it.

Other purposes will be appreciated as details of the principles of theinvention and features of its construction are outlined. -For a betterunderstanding of the invention and its objects, reference is made to theappended drawings and the description following, which togetherillustrate a particular form of the invention, while the scope of theinvention is emphasized in the claims;

The'drawings indicate the particular form of the invention as anexample, andin the figures:

F-igurel is a view inperspective of the tester, embodying thisinvention;

Figure 2 is a sectional view taken through the tester;

Figure 3 is a sectional view taken through the procls;.

Figure 4 .is a diagrammatic wiring diagram showing the connections usedfor reading A CIT".

voltage; V g

Figure 5 .is a diagrammatic wiring diagram showing-the connections usedfor reading M. A.;.

Figure 6 is a diagrammatic wiring showingthe connections used forreading ohms, and

Figure '7 is a diagrammatic wiring diagram showing the connections usedfor reading D. C. voltage. I r

Similar reference numerals are used to designate the same elements inall the drawings.

In the particular construction shown, a cylindrical housing I0 containsthe operating elements within various chambers provided in its interior.

A dial I I, with suitable meter indices or markings I 2. and anoscillating needle 13, are provided at one endof the housing III, andcovered or proparent enough to permit easy inspection. This dial II andincidentals are limited in dimensions is screwed or fittedon the housingto come flush with its peripheral surface and is called the cap. A pairof flexible cables I6 extend from the opposite end of the housing,termed the bottom. These cables I-6 contain stranded conductors..- whiohare coupled to the network within the housing IIL; They passthroughholes I1 in a plug I8 fitted in at this end, of the housing, and held inposition-by a circular. frame Ill. The cables I6 are made long enoughtosuit the use intended for themand topermit their facile" manipulation.They; terminate in long handles 20 and 200 of insulating material whichhave pointed prods; I9 and I Of conducting-metal 1 These prods I9 andI90 are con 9 at their ends. nected tofuse links I19 and are coupled tothe cables I6 and are activated thereby to permit testing of theextraneous equipment brought for-- ward for such purpose.

The interior structure of this particular device is adapted-to measurethe electrical energy or effects for four requirements. These are thedirect current voltage of the circuit or the drop in E. M. F. acrossapart of a network; the current flowing ina network; the resistance of anetwork or portion thereof; and the voltage or current of an alternatingcurrent characteristic;

thereof. The details of the network are indicell battery ZI of theflashlight type.

and 2'! leading from them for connections to be made during'theoperation of the device in pre-;-- The negative side 28 of the battery2| is left free to be closed at 40 on the meter 30 in various ways asthe operation Y determined sequence.

may require for the specific uses involved at the moment. Its mainoperative connection is intended to be made to the works of the meter 30that operates the'needle I3. The works include the general elements of ameter for measuring" the electrical energy'involved. A rheosta't or po-'tentiometer 39 also connects' 'in the circuit and;

to the'meter30. i

There is also a bridge rectifier 42 preferably of the electrolytic typehaving four terminals 43, 44, 45 and 48. Terminal 44 connects withcontactor 89 mounted on ring 59 and passes to meter leg 40, through themeter and out the outer leg M to the contactor 84 to terminal 46.Terminal 45 connects with contactor I83 mounted on ring 53 and passes toring 64 thence through the cable l6 and prod- I90. The terminal. 43 is.in circuitwith the lil volt, 106 volt and 1000 volt resistances 45, 41and 48 respectively which in turn are taped at 49, 55 and and connectwith contactors 49,

50 and 5| mounted on ring =52 and passes to ring 5| thence through thecable I6 andprod i9;- These various parts or elementsare-likewise-identified on the structure itself. However to hold theparts suitably in the housing I ILthemeter 30 is firmly secured in thehousing and contact. is made therewith by the meter legs 50, and 53"which touch the terminals 83 and 84 respectively. The potentiometer 39is assembled to a tubular cylinder 55" and is mounted on the plug isthatfits in the housing I-"U" at'the' endopposite to the meter 38', andis controlled by the rotative han die 54 extending exteriorly'therefrom. This cylinder 55" extends into: the housing about half wayand'term-inateswith a disc plateorring 5a whichis" of a diametersuffi'cien't to frictionally path of the current in the diagram will beeither through resistors 3|, 32 and 33 according to the voltage to betested. If the voltage to be tested is known to be less than volts, thenthe tap or contactor 34 is coupled to 3I. The current will then flowthrough the network indicated in Figure 7 as follows. Through prod [9,to the conducting ring GI, thence through 1! to ring 82. Thence itpasses to contactor 34, resistorv 3|, to contactor 8'3,v then to meter38, to contactor 84 to ring I83, on ring 63, through 16, to ring 64,then to cables and prod I90. The meter 30 will then indicate the valuesof the tested outside equip'ment'coupled to it by the prods I9 and I90.Ifthe test is for ohms, the cylinder 55 is rotated until the line ofnumerals representing ohmsonthehousihgfbr the proper ohmage align withthe arrow 58 formed on the cylinder 55.

engage with the wall 51 about the chamber 58 foriiied in the housing. Inconjunction with another similar plate of ring 59", and a series ofstuds 66 it forms a; frame work and spacing for thebattery 2i and tosupport the various resist mines and rectifier 4 2 and otherconnections. The connections being" arranged suitably therein to suitthe networks used and where their ter min'als' should be coupledto.including the meter legs 50 and 53. The cylinder 55- is" surroundedperipherally by the ring 6| which is connected to prod I9. The ring 64'is connected to prod I983 Thering's" Bland G2 connect with rings- 8-:and 54 respectively which are of conducting material and are within thewall 5''? ofthe housing andthe respective contact members; The rings GI,62; 53' and 64 are spaced apart by collars 39, 10', II and I2 of varyingwidths positioned on the sleeve- 6-1 of'cylinder to keepthem separatedat appropriate electrical distances. These col-- lar'sand rings arefastened on the sleeve 5'! secur'e'ly so they become part of thecylinder 55 and interior" elements as a unit. A groove 13 is pro videdin the collar It to serve as a lock when a setscrew '54 is threadedthrough the housing wall F8 into it. Embedded in the housing wall5'I'are connectors or contactors Ti and Isthat serve to close thenetwork in certain pred'eter' mined parts when the cylinder is rotatedwithin-v the housing to a predetermined position. A clicker 80 isoperated by cylinder 55 whenever the cylinder is turnedand passes anoperating positiorr in which the connections are registered properly forthe particular tests to be made by it.

In the sections in Figure 2- are shown the manner in which the housingis arranged with the contactors and rings. A zero on the meter shows thepositionto which the needle I3 is pointed when no test" is being made orthe testis neutral.

In the operation of the device, the prods and I 9 0' are rested on theenergized points of the equipment to be tested. If the test is for D.-C.

voltage, the: cylinder 55 is rotated until the line of numerals E5 and86 on the housing for theproper. voltage aligns with the arrow 50 formedl1 on-the cylinder 55. This aligns the connections.

inside the housing for this particulartest The This al'ig'ns theconnections inside the housing for this particular test. The path of thecurrent inthe diagram will be either through the resistors 22', 23 and24 according to the ohmage to be" tested. If" the ohms to be tested is"known to be less than 100' ohms, then the tap or contactor 25* The"current will then flow through the network indicated in Figure G'a's'fQlis coupled to 22.

lows. 7 Through prod I9, to the conducting ring 6|, thence through II!to ring '82. Thence it passes to contactor 25, resistor 22 to positiveside of battery 2'! then from the negative side of said battery tocontactor 85, then to-t'he-meter leg40, then to the rheostat 39 to meterleg 4|, then to contactor 84 to ring I83 on the'ring" 6-3, througlr' I6,to ring'34, then tocables and prod I921. The i meter'38 will: thenindicate thevalues in ohms of the tested outside equipment coupled toitby the prods I9 and ISO.

The current test is likewise" shown in Figure 5. In this instance, thedevice is'particul'arly adapted for small amperage. The cylinder 55- is'turned until the arrow 50 aligns with the proximate amperage resistors31', I31, or 23'! to be utilized. 1 The current then passes from thetested equi'pment through the-prod I9 and consecutively follows throughthe parts 31 (or I31 or 23?)" to 84 on 59, to meter 30, to contactorI83, to ring 63,

16, ring 64 to prod I93.

For the A. C. test of voltage, the current passes through the prod i9,rings SI and E2, connection 11, contactor ring 62 and selectedcontactors 49, 58, 5 through the selected resistors 45, 4'! or 48 to therectifier 42. Thence to contactor 84 to meter 38 to contactor 89,through rectifier 4-2, to

rings 63 and 54 to prod I 98.

The operator simply revolves the cylinder 55 t of the device" until thearrow 58 register'swith' the corresponding marking to be used. for the 1I This automatically arranges the elements within the housing totheir-proper alignment to produce the desired network, and enables the'meter to give the readings desired when the I test.

prods I9 and I98 areapplied appropriately The unit is compact and avoidsthe use of sev-;

eral pieces of equipment normally required in such tests although it isenabled to make many different kind of tests.

mechanical injury by the housing. The handles 28 and 200, prods I3 and Iand cables permit flexible coupling over considerable area. The

It can be made relatively 5 water proof, its elements are protected from5 operation is the potentiometer 39 and this is accomplished readily byturning the handle 56 placed very conveniently. The meter 30 can also beremoved as it is held in by the screw threaded frame [5 that is readilydetached, to permit access thereto.

The housing is provided with a suitable slot id in its peripheral wall,in which a clip 78 can be used removably for enabling the unit to becarried around in the pocket of the user.

While the construction shown in the drawings and described in thespecifications indicates only one general structure, and is capable ofmaking several distinct tests, it is not desired to limit the scope ofthe invention to that particular form as it is appreciated that otherforms of constructions could be developed and used that would employ thesame principles and come within the scope of the appended claims.

Having thus described the invention what is claimed is:

1. A combined electrical portable measuring apparatus for determiningthe values of A. C. voltage, current, resistance and D. C. voltage ofelectric circuits, comprising a cylindrical casing, an indicator dialand an indicating needle mounted at one end of the casing, a cylindricalsleeve rotatably secured at the opposite end of said casing, a pair ofprods extending through and outwardly of said cylindrical sleeve, aplurality of electrical circuits within said cylindrical casing adaptedto be selectively placed in circuit with said prods and indicatingneedle when the prods are used to determine the voltage, current andresistance to be measured, said circuits including a plurality ofrotatable rings to selectively close and open the circuits, said,cylindrical casing bearing outward indicia corresponding to current,voltage and resistance values, and connecting means between saidcylindrical sleeve and said rings to selectively rotate said rings andclose and open the aforesaid circuits, said sleeve bearing an outersymbol indicating the position of the sleeve with respect to the indiciaon the cylindrical casing.

2. A combined electrical portable measuring apparatus as set forth inclaim 1, a snap connection between said casing and said sleeve toyieldingly retain said sleeve in its position of adjustment.

3. A combined electrical portable measuring apparatus as set forth inclaim 1 including a handle secured on said casing.

' THOMAS L. BARTHOLOMEW.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

